Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.5.4 (SOR)
720 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The herbicide acifluorfen (2-chloro-4-(trifluoromethyl)phenoxy-2-nitrobenzoate) causes strong photooxidative destruction of pigments and lipids in sensitive plant species. Antioxidants and oxygen radical scavengers slow the bleaching action of the herbicide. The effect of acifluorfen on glutathione and ascorbate levels in cucumber (Cucumis sativus L.) cotyledon discs was investigated to assess the relationship between herbicide activity and endogenous antioxidants. Acifluorfen decreased the levels of glutathione and ascorbate over 50% in discs exposed to less than 1.5 hours of white light (450 microeinsteins per square meter per second). Coincident increases in dehydroascorbate and glutathione disulfide were not observed. Acifluorfen also caused the rapid depletion of ascorbate in far-red light grown plants which were photosynthetically incompetent.Glutathione reductase, dehydroascorbate reductase, superoxide dismutase, ascorbate oxidase, ascorbate free radical reductase, peroxidase, and catalase activities rapidly decreased in acifluorfen-treated tissue exposed to white light. None of the enzymes were inhibited in vitro by the herbicide. Acifluorfen causes irreversible photooxidative destruction of plant tissue, in part, by depleting endogenous antioxidants and inhibiting the activities of protective enzymes.
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PMID:Effects of Acifluorfen on Endogenous Antioxidants and Protective Enzymes in Cucumber (Cucumis sativus L.) Cotyledons. 1666 6

Large changes occur in the ascorbate system during the development of Vicia faba seed and these appear closely related to what are generally considered to be the three stages of embryogenesis. During the first stage, characterized by embryonic cells with high mitotic activity, the ascorbic acid/dehydroascorbic acid ratio is about 7, whereas in the following stage, characterized by rapid cell elongation (stage 2), it is lower than 1. The different ascorbic/dehydroascorbic ratio may be correlated with the level of ascorbate free radical reductase activity, which is high in stage 1 and lower in stage 2. Ascorbate peroxidase activity is high and remains constant throughout stages 1 and 2, but it decreases when the water content of the seed begins to decline (stage 3). In the dry seed, the enzyme disappears together with ascorbic acid. Ascorbate peroxidase activity is observed to be 10 times higher than that of catalase, suggesting that ascorbate peroxidase, rather than catalase, is utilized in scavenging the H(2)O(2) produced in the cell metabolism. There is no ascorbate oxidase in the seed of V. faba. V. faba seeds acquire the capability to synthesize ascorbic acid only after 30 days from anthesis, i.e. shortly before the onset of seed desiccation. This suggests that (a) the young seed is furnished with ascorbic acid by the parent plant throughout the period of intense growth, and (b) it is necessary for the seed to be endowed with the ascorbic acid biosynthetic system before entering the resting state so that the seed can promptly synthesize the ascorbic acid needed to reestablish metabolic activity when germination starts.
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PMID:Changes in the Ascorbate System during Seed Development of Vicia faba L. 1666 55

The physiological effects of lanthanum(III) ions on the ferritin-regulated antioxidant process were studied in wheat (Triticum aestivum L.) seedlings under polyethylene glycol (PEG) stress. Treatment with 0.1 mM La3+ resulted in increased levels of chlorophyll, carotenoid, proline, ascorbate, and reduced glutathione. The activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and peroxidase were also increased after La3+ treatment. Treatment with La3+ seems to enhance the capacity of the reactive oxygen species scavenging system, affect the Fe2+ and Fe3+ electron-transfer process in ferritin, and restrain the formation of hydroxyl radical (OH.), alleviating the oxidative damage induced by PEG stress.
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PMID:Effect of lanthanum ions (La3+) on ferritin-regulated antioxidant process under PEG stress. 1719 21

Ascorbate is the most abundant small molecule antioxidant in plants and is proposed to function, along with other members of an antioxidant network, in controlling reactive oxygen species. A biochemical and molecular characterization of four ascorbate-deficient (vtc) Arabidopsis thaliana mutants has been carried out to determine if ascorbate deficiency is compensated by changes in the other major antioxidants. Seedlings grown in vitro were used to minimize stress and longer term developmental differences. Comparison was made with the low glutathione cad2 mutant and vtc2-1 treated with D,L-buthionine-[S,R]-sulphoximine to cause combined ascorbate and glutathione deficiency. The pool sizes and oxidation state of ascorbate and glutathione were not altered by deficiency of the other. alpha-Tocopherol and activities of monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and catalase were little affected. Ascorbate peroxidase activity was higher in vtc1, vtc2-1, and vtc2-2. Ionically bound cell wall peroxidase activity was increased in vtc1, vtc2-1, and vtc4. Supplementation with ascorbate increased cell wall peroxidase activity. 2,6-Dichlorobenzonitrile, an inhibitor of cellulose synthesis, increased cell wall peroxidase activity in the wild type and vtc1. The transcript level of an endochitinase, PR1, and PR2, but not GST6, was increased in vtc1, vtc2-1, and vtc-2-2. Endochitinase transcript levels increased after ascorbate, paraquat, salicylic acid, and UV-C treatment, PR1 after salicylic acid treatment, and PR2 after paraquat and UV-C treatment. Camalexin was higher in vtc1 and the vtc2 alleles. Induction of PR genes, cell wall peroxidase activity, and camalexin in vtc1, vtc2-1, and vtc2-2 suggests that the mutants are affected in pathogen response signalling pathways.
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PMID:Antioxidant status, peroxidase activity, and PR protein transcript levels in ascorbate-deficient Arabidopsis thaliana vtc mutants. 1884 95

Senescence is a developmentally regulated and highly ordered sequence of events. Senescence leads to abscission of plant organs and eventually leads to death of a plant or part of it. Present study revealed that Phalaenopsis flower undergo senescence due to over activation of O(2) (.-)generating xanthine oxidase (XO), which consequently increases the concentrations of O(2) (.-) leading to enhanced oxidative damage and disturbed cellular redox environment as indicated by increased lipid peroxidation and DHA/AsA + DHA ratio, respectively. While activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and non-specific peroxidase (POD) were enhanced in sepals and petals of old flower, activities of catalase (CAT) and glutathione reductase (GR) were decreased. Exogenous application of nitric oxide (NO) retarded H(2)O(2)-induced senescence of Phalaenopsis flower by downregulating activity of XO and concentrations of O(2) (.-), H(2)O(2) and malondialdehyde (MDA, an index of lipid peroxidation). Exogenous application of NO also downregulated SOD activity and upregulated antioxidant enzymes involved in the detoxification of H(2)O(2) (CAT and APX), and in the regulation of redox couples viz, monodehydroascorbate reductase (MDHAR) and GR, together with the modulation in non-protein thiol status and DHA/AsA + DHA ratio.
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PMID:Nitric oxide retards xanthine oxidase-mediated superoxide anion generation in Phalaenopsis flower: an implication of NO in the senescence and oxidative stress regulation. 1898 52

Dunaliella species accumulate carotenoids and their role in protection against photooxidative stress has been investigated extensively. By contrast, the role of other antioxidants in this alga, has received less attention. Therefore, the components of the ascorbate-glutathione cycle, along with superoxide dismutase (E.C. 1.15.1.1) and peroxidase (E.C. 1.11.1.11) activity were compared in two strains of Dunaliella salina. Strain IR-1 had two-fold higher chlorophyll and beta-carotene concentration than Gh-U. IR-1 had around four-fold higher superoxide dismutase, ascorbate peroxidase and pyrogallol peroxidase activities than Gh-U on a protein basis. Ascorbate and glutathione concentrations and redox state did not differ between strains and there was little difference in the activity of ascorbate-glutathione cycle enzymes (monodehydroascorbate reductase [E.C. 1.6.5.4], dehydroascorbate reductase [E.C. 1.8.5.1] and glutathione reductase [E.C. 1.8.1.7]). The response of these antioxidants to high light and low temperature was assessed by transferring cells from normal growth conditions (28 degrees C, photon flux density of 100 micromol m(-2) s(-1))to 28 degrees C/1200 micromol m(-2) s(-1); 13 degrees C/100 micromol m(-2) s(-1); 13 degrees C/1200 micromol m(-2) s(-1) and 28 degrees C/100 micromol m(-2) s(-1) for 24 h. Low temperature and combined high light-low temperature decreased chlorophyll and beta-carotene in both strains indicating that these treatments cause photooxidative stress. High light, low temperature and combined high light-low temperature treatments increased the total ascorbate pool by 10-50% and the total glutathione pool by 20-100% with no consistent effect on their redox state. Activities of ascorbate-glutathione cycle enzymes were not greatly affected but all the treatments increased superoxide dismutase activity. It is concluded that D. salina can partially adjust to photooxidative conditions by increasing superoxide dismutase activity, ascorbate and glutathione.
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PMID:The effect of acute high light and low temperature stresses on the ascorbate-glutathione cycle and superoxide dismutase activity in two Dunaliella salina strains. 1923 61

Apple replant is a widespread agricultural problem documented in all of the major fruit-growing regions of the world. In order to better understand the phytotoxic mechanisms induced by allelochemicals involved with this problem, Malus prunifolia plants were grown hydroponically to the six-leaf-stage in the presence of phthalic acid (0 or 1 mM) for 5, 10, or 15 days. Apple plants were evaluated for: shoot and root length, fresh and dry weight, malondialdehyde (MDA) content, hydrogen peroxide (H(2)O(2)) content, superoxide radical (O(2) (*-)) generation rate, and antioxidant enzyme activities. Shoot and root lengths and fresh and dry weights of M. prunifolia decreased in plants exposed to phthalic acid. MDA and H(2)O(2) content increased in phthalic acid-treated plants as did the generation rate of O(2) (*-) in M. prunifolia roots. The activities of superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), glutathione reductase (EC 1.6.4.2), dehydroascorbate reductase (EC 1.8.5.1), and monodehydroascorbate reductase (EC 1.6.5.4) increased in phthalic acid-stressed roots compared with control roots. These results suggest that activation of the antioxidant system by phthalic acid led to the formation of reactive oxygen species that resulted in cellular damage and the decrease of M. prunifolia growth.
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PMID:Phthalic acid induces oxidative stress and alters the activity of some antioxidant enzymes in roots of Malus prunifolia. 1935 74

The effect of different cadmium (Cd) concentrations (5, 50 and 500 microM) on growth, Cd accumulation and antioxidative systems was studied in Paxillus involutus, grown in liquid medium. Cd was rapidly accumulated by P. involutus and resulted in growth inhibition within 24 h. Antioxidative enzymes (superoxide dismutase (SOD), EC 1.15.1.1; catalase (CAT), EC 1.11.1.6; monodehydroascorbate radical reductase (MDAR), EC 1.6.5.4; dehydroascorbate reductase (DAR) glutathione reductase (GR), EC 1.8.1.7 and glutathione-dependent peroxidase (GPx), EC 1.11.1.9) were active in the investigated fungus. Furthermore, high concentrations of glutathione but no ascorbate were detected. Cd exposure resulted in a significant induction of SOD activity. However, activities of enzymes responsible for the detoxification of H2O2 showed no Cd-dependent increase or were only transiently induced (CAT, GPx) and no accumulation of H2O2 was detected. Exposure to low Cd concentrations (5 and 50 microM) caused an increase in GR, while 500 microM Cd led to an inhibition of GR and CAT. Increased glutathione concentrations were observed as a consequence of all Cd treatments. These results suggest that the antioxidative protection of the investigated strain of P. involutus was sufficient to avoid Cd-mediated oxidative stress. It is likely that this strain was able to detoxify high concentrations of Cd by transport of Cd into the vacuole because a high correlation between Cd and sulphur in the vacuole was detected by EDX.
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PMID:Characterisation of antioxidative systems in the ectomycorrhiza-building basidiomycete Paxillus involutus (Bartsch) Fr. and its reaction to cadmium. 1970 95

Plants have evolved mechanisms to avoid and repair UV radiation damage, and the free radicals caused by UV tend to be involved in the induction of antioxidant defense systems. In this study, changes in resveratrol and antioxidant enzymes were investigated in relation to UV damage in peanut seedlings. Accumulation of endogenous resveratrol and stilbene synthase mRNA occurred rapidly and significantly in response to UV-C irradiation. Applying resveratrol before UV-C irradiation mitigated rusty spots and wilting of peanut leaves, and inhibition of resveratrol by applying 3,4-methylenedioxycinnamic acid worsened UV-C damage, an effect that was found to be concentration dependent. Correspondingly, the effect of resveratrol on malondialdehyde was similar to changes in the apparent morphology of seedling leaves. Changes in H(2)O(2), O(2)(-), and antioxidant enzymes showed some similarities after either UV-C irradiation or resveratrol treatment. Activities of superoxide dismutases, glutathione reductase, and catalase were more than 2-fold higher during the first 1h after treatments. Ascorbate peroxidase activity increased to more than 3-fold higher 24h after irradiation, whereas it was more than 2-fold higher 8h after resveratrol treatment. Activities of dehydroascorbate reductase and monodehydroascorbate reductase increased by 40% during 8-24h after treatments. Consequently, we proposed that changes in endogenous resveratrol and in antioxidant enzymes may have been involved in oxidative stress induced by UV-C exposure in peanut seedlings.
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PMID:Changes of resveratrol and antioxidant enzymes during UV-induced plant defense response in peanut seedlings. 1971 23

The effect of acidified calcium sulfate (ACS) on the quality of litchi ( Litchi chinensis Sonn. cv. 'Brewster') fruit after harvest was evaluated. ACS at 1.25% or higher concentrations significantly inhibited the activities of polyphenol oxidase and peroxidase in the pericarp during storage at both 5 and 10 degrees C. These treatments also effectively prevented browning and retained the red color of the outer shell of the fruit. Total phenolic and total anthocyanin contents in pericarp were increased by ACS treatments in a dose-dependent manner. The radical scavenging activities for ROO(*), DPPH(*), (*)OH and O(2)(*-) were also enhanced by ACS, particularly by 2.5 and 5% concentrations. The activities of several antioxidant enzymes and enzymes of ascorbate-glutathione cycle including catalase, ascorbate peroxidase, glutathione peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase gradually declined during storage. However, ACS enhanced the activities of these enzymes, especially at the beginning of the storage. Samples treated with ACS generally had higher flavonoid levels than the control. The three major flavonoids, cyanidin-3-rutinoside, cyanidin-3-glucoside and quercetin-3-rutinoside, were found to be significantly increased by 2.5 and 5.0% ACS at both 5 and 10 degrees C. No differences were detected among various treatments in soluble solids content or sugar and organic acid levels in the pulp of litchi fruit, indicating that the internal quality of the fruit was not adversely affected by ACS treatment.
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PMID:Maintaining quality of litchi fruit with acidified calcium sulfate. 2061 5


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